In building complex structures such as aircraft, buildings or ships a need arises to model physical conditions on the structure. Often this is accomplished using scale models of the structure in environmental chambers such as wind tunnels or wave tanks. This enables an understanding of the expected performance or design flaws of the structure prior to actually building the structure itself. For example, physical conditions such as pressure can be measured with transducers placed on the various surfaces (wings, tail, nose etc.) of a wind tunnel model. The data measured by the transducers can then be recorded and analyzed.
Transducers are typically installed by drilling holes and passages in the model for wires that run to the transducers located in or on the model, or air tubes that run to remotely located transducers. The problem arises in that placing transducers on the model in this manner makes the model very expensive to build and the number, location and position of the transducers limited. Therefore the amount of data available becomes limited.
An additional problem arises when testing actual conditions on the full scale structures. In flight testing of an airplane, one may want to install sensors on the aircraft in order to measure pressure on the leading edges, the wing and other various aerodynamic surfaces. This involves a great expense in placing the sensors inside the aircraft with a plethora of wires or air tubes running throughout the aircraft.
One solution that has attempted to increase the number of sensors point available on the structure has been to utilize Micro Electrical Mechanical Devices (MEMS). MEMS offer the integration of micro-machined mechanical devices and microelectronics on a single chip. These electromechanical devices may include discrete sensors to measure conditions such as pressure, vibration, temperature, sound and the like. To put these devices on or in a structural model inside an environmental chamber such as a wind tunnel model could be an advantage. The MEMS devices may include multiple sensors in one package to monitor conditions simultaneously. However, the plethora of wiring is still required to both power the MEMS and transfer the data gathered by the MEMS. Therefore no significant practical or cost savings can be achieved by the use of these devices unless there is supplied power from internal sources such as batteries or battery assisted circuits. The current remote sensors for Prognostics or Identification RF transmission requires battery assisted power source in order to transmit data because insufficient power is harvested through the current technology and design. Thus these devices have a limited lifetime determined by their battery life.